If the electric current (or the magnetic field) is alternating, the rod will begin torsional oscillation.
In linear approach angle of rod torsion α does not depend on its cross-section form and is defined only by current density and magnetoelastic properties of the rod:[2] where Magnetostrictive position sensors use the Wiedemann effect to excite an ultrasonic pulse.
Typically a small magnet is used to mark a position along a magnetostrictive wire.
The time required for this pulse to travel from the point of excitation to a pickup at the end of the wire gives the position.
In order to avoid this the wire is connected to a mechanical damper that end.